diff --git a/packages/features/bookings/lib/getBookingResponsesSchema.ts b/packages/features/bookings/lib/getBookingResponsesSchema.ts
index e4be05e95db..cf9c396eeb0 100644
--- a/packages/features/bookings/lib/getBookingResponsesSchema.ts
+++ b/packages/features/bookings/lib/getBookingResponsesSchema.ts
@@ -200,8 +200,9 @@ async function superRefineField({
     }
 
     const emails = emailsParsed.data;
-    emails.sort().some((item, i) => {
-      if (item === emails[i + 1]) {
+    const sortedEmails = [...emails].sort();
+    sortedEmails.some((item, i) => {
+      if (item === sortedEmails[i + 1]) {
         zodCtx.addIssue({ code: z.ZodIssueCode.custom, message: m("duplicate_email") });
         return true;
       }
diff --git a/packages/lib/CalEventParser.test.ts b/packages/lib/CalEventParser.test.ts
index bf6a50f4821..12b5350ba42 100644
--- a/packages/lib/CalEventParser.test.ts
+++ b/packages/lib/CalEventParser.test.ts
@@ -3,7 +3,7 @@ import { describe, expect, it } from "vitest";
 
 import type { CalendarEvent } from "@calcom/types/Calendar";
 
-import { getRichDescription, getUserFieldsResponses } from "./CalEventParser";
+import { getProviderName, getRichDescription, getUserFieldsResponses } from "./CalEventParser";
 
 describe("getRichDescription", () => {
   const t = ((key: string, _args?: Record<string, unknown>) => key) as TFunction;
@@ -86,6 +86,26 @@ describe("getRichDescription", () => {
   });
 });
 
+describe("getProviderName", () => {
+  it("should return empty string for integrations: with no provider", () => {
+    expect(getProviderName("integrations:")).toBe("");
+  });
+
+  it("should return capitalized provider name", () => {
+    expect(getProviderName("integrations:daily")).toBe("Cal Video");
+    expect(getProviderName("integrations:zoom")).toBe("Zoom");
+  });
+
+  it("should return empty string for null/undefined", () => {
+    expect(getProviderName(null)).toBe("");
+    expect(getProviderName(undefined)).toBe("");
+  });
+
+  it("should return URL as-is for http locations", () => {
+    expect(getProviderName("https://zoom.us/j/123")).toBe("https://zoom.us/j/123");
+  });
+});
+
 describe("getUserFieldsResponses", () => {
   const t = ((key: string) => key) as TFunction;
 
diff --git a/packages/lib/CalEventParser.ts b/packages/lib/CalEventParser.ts
index c7388c3639a..1fe72ee7b9d 100644
--- a/packages/lib/CalEventParser.ts
+++ b/packages/lib/CalEventParser.ts
@@ -200,6 +200,7 @@ export const getLocation = (calEvent: {
 export const getProviderName = (location?: string | null): string => {
   if (location && location.includes("integrations:")) {
     let locationName = location.split(":")[1];
+    if (!locationName) return "";
     if (locationName === "daily") {
       locationName = "Cal Video";
     }
diff --git a/packages/lib/constants.ts b/packages/lib/constants.ts
index 5401ca25ccf..72c092c5c0c 100644
--- a/packages/lib/constants.ts
+++ b/packages/lib/constants.ts
@@ -137,8 +137,17 @@ export const API_NAME_LENGTH_MAX_LIMIT = 80;
 export const MINUTES_TO_BOOK = process.env.NEXT_PUBLIC_MINUTES_TO_BOOK || "5";
 export const ENABLE_PROFILE_SWITCHER = process.env.NEXT_PUBLIC_ENABLE_PROFILE_SWITCHER === "1";
 // Needed for orgs
-export const ALLOWED_HOSTNAMES = JSON.parse(`[${process.env.ALLOWED_HOSTNAMES || ""}]`) as string[];
-export const RESERVED_SUBDOMAINS = JSON.parse(`[${process.env.RESERVED_SUBDOMAINS || ""}]`) as string[];
+const safeParseCsvEnvVar = (envVar: string | undefined): string[] => {
+  if (!envVar) return [];
+  try {
+    return JSON.parse(`[${envVar}]`);
+  } catch {
+    return envVar.split(",").map((s) => s.trim().replace(/^"|"$/g, ""));
+  }
+};
+
+export const ALLOWED_HOSTNAMES = safeParseCsvEnvVar(process.env.ALLOWED_HOSTNAMES);
+export const RESERVED_SUBDOMAINS = safeParseCsvEnvVar(process.env.RESERVED_SUBDOMAINS);
 
 export const ORGANIZATION_SELF_SERVE_PRICE = parseFloat(
   process.env.NEXT_PUBLIC_ORGANIZATIONS_SELF_SERVE_PRICE_NEW || "37"
diff --git a/packages/lib/contructEmailFromPhoneNumber.ts b/packages/lib/contructEmailFromPhoneNumber.ts
index 63d73a4e383..72477d91465 100644
--- a/packages/lib/contructEmailFromPhoneNumber.ts
+++ b/packages/lib/contructEmailFromPhoneNumber.ts
@@ -1,4 +1,5 @@
 export const contructEmailFromPhoneNumber = (phoneNumber: string) => {
+  if (!phoneNumber) return "";
   const cleanedPhoneNumber = phoneNumber.replace(/\+/g, "");
   return `${cleanedPhoneNumber}@sms.cal.com`;
 };
diff --git a/packages/lib/csvUtils.test.ts b/packages/lib/csvUtils.test.ts
new file mode 100644
index 00000000000..759df92921c
--- /dev/null
+++ b/packages/lib/csvUtils.test.ts
@@ -0,0 +1,52 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { downloadAsCsv, objectsToCsv, sanitizeValue } from "./csvUtils";
+
+afterEach(() => {
+  vi.restoreAllMocks();
+});
+
+describe("sanitizeValue", () => {
+  it("returns simple values unchanged", () => {
+    expect(sanitizeValue("hello")).toBe("hello");
+  });
+
+  it("wraps values with commas in quotes", () => {
+    expect(sanitizeValue("hello,world")).toBe('"hello,world"');
+  });
+
+  it("wraps values with newlines in quotes", () => {
+    expect(sanitizeValue("hello\nworld")).toBe('"hello\nworld"');
+  });
+
+  it("doubles quotes and wraps values containing double quotes", () => {
+    expect(sanitizeValue('he said "hello"')).toBe('"he said ""hello"""');
+  });
+
+  it("handles values with quotes and commas", () => {
+    expect(sanitizeValue('he said "hello", world')).toBe('"he said ""hello"", world"');
+  });
+
+  it("prefixes formula-trigger characters with single quote to prevent injection", () => {
+    expect(sanitizeValue("=HYPERLINK(http://evil.com)")).toBe("'=HYPERLINK(http://evil.com)");
+    expect(sanitizeValue("+SUM(A1:A10)")).toBe("'+SUM(A1:A10)");
+    expect(sanitizeValue("-SUM(A1:A10)")).toBe("'-SUM(A1:A10)");
+    expect(sanitizeValue("@SUM(A1:A10)")).toBe("'@SUM(A1:A10)");
+  });
+
+  it("does not prefix non-formula values", () => {
+    expect(sanitizeValue("hello")).toBe("hello");
+    expect(sanitizeValue("123")).toBe("123");
+    expect(sanitizeValue("john@example.com")).toBe("john@example.com");
+  });
+});
+
+describe("objectsToCsv", () => {
+  it("handles values with newlines correctly", () => {
+    const data = [
+      { name: "Alice", note: "hello\nworld" },
+      { name: "Bob", note: "normal" },
+    ];
+    const csv = objectsToCsv(data);
+    expect(csv).toBe('name,note\nAlice,"hello\nworld"\nBob,normal');
+  });
+});
diff --git a/packages/lib/csvUtils.ts b/packages/lib/csvUtils.ts
index 5746c433b3d..bc5cb93f085 100644
--- a/packages/lib/csvUtils.ts
+++ b/packages/lib/csvUtils.ts
@@ -57,5 +57,11 @@ export const sanitizeValue = (value: string) => {
   if (value.includes(",") || value.includes("\n")) {
     return `"${value}"`;
   }
+  // Protect against formula injection (OWASP). Values starting with =, +, -, @
+  // are interpreted as formulas by Excel/Sheets. Prefix with a single quote to
+  // force text rendering, which is invisible in most spreadsheet apps.
+  if (/^[=+\-@]/.test(value)) {
+    return `'${value}`;
+  }
   return value;
 };
diff --git a/packages/lib/errors.ts b/packages/lib/errors.ts
index 29613e129b4..28d34ccd1da 100644
--- a/packages/lib/errors.ts
+++ b/packages/lib/errors.ts
@@ -64,7 +64,7 @@ export async function handleErrorsJson<Type>(response: Response): Promise<Type>
     return new Promise((resolve) => resolve({} as Type));
   }
 
-  if (!response.ok && (response.status < 200 || response.status >= 300)) {
+  if (!response.ok) {
     response.json().then(console.log);
     throw Error(response.statusText);
   }
diff --git a/packages/lib/extract-base-email.test.ts b/packages/lib/extract-base-email.test.ts
new file mode 100644
index 00000000000..7c5aea79669
--- /dev/null
+++ b/packages/lib/extract-base-email.test.ts
@@ -0,0 +1,21 @@
+import { describe, expect, it } from "vitest";
+
+import { extractBaseEmail } from "./extract-base-email";
+
+describe("extractBaseEmail", () => {
+  it("should extract base email removing plus aliases", () => {
+    expect(extractBaseEmail("user+alias@example.com")).toBe("user@example.com");
+  });
+
+  it("should return email unchanged if no plus alias", () => {
+    expect(extractBaseEmail("user@example.com")).toBe("user@example.com");
+  });
+
+  it("should return input unchanged if no @ sign", () => {
+    expect(extractBaseEmail("notanemail")).toBe("notanemail");
+  });
+
+  it("should handle empty string", () => {
+    expect(extractBaseEmail("")).toBe("");
+  });
+});
diff --git a/packages/lib/extract-base-email.ts b/packages/lib/extract-base-email.ts
index a687011000f..f6f251d28f9 100644
--- a/packages/lib/extract-base-email.ts
+++ b/packages/lib/extract-base-email.ts
@@ -1,6 +1,9 @@
 // Function to extract base email
 export const extractBaseEmail = (email: string): string => {
-  const [localPart, domain] = email.split("@");
+  const atIndex = email.indexOf("@");
+  if (atIndex === -1) return email;
+  const localPart = email.substring(0, atIndex);
+  const domain = email.substring(atIndex + 1);
   const baseLocalPart = localPart.split("+")[0];
   return `${baseLocalPart}@${domain}`;
 };
diff --git a/packages/lib/formatPhoneNumber.ts b/packages/lib/formatPhoneNumber.ts
index 1fcf66110cd..940654909a1 100644
--- a/packages/lib/formatPhoneNumber.ts
+++ b/packages/lib/formatPhoneNumber.ts
@@ -1,6 +1,10 @@
 import { parsePhoneNumberWithError } from "libphonenumber-js/max";
 
 export const formatPhoneNumber = (phoneNumber: string) => {
-  const parsedPhoneNumber = parsePhoneNumberWithError(phoneNumber);
-  return parsedPhoneNumber?.isValid() ? parsedPhoneNumber.formatInternational() : phoneNumber;
+  try {
+    const parsedPhoneNumber = parsePhoneNumberWithError(phoneNumber);
+    return parsedPhoneNumber?.isValid() ? parsedPhoneNumber.formatInternational() : phoneNumber;
+  } catch {
+    return phoneNumber;
+  }
 };
diff --git a/packages/lib/getIP.ts b/packages/lib/getIP.ts
index 1962b417ced..ed0cc39785c 100644
--- a/packages/lib/getIP.ts
+++ b/packages/lib/getIP.ts
@@ -37,7 +37,12 @@ const banlistSchema = z.array(z.string());
 export function isIpInBanlist(request: Request | NextApiRequest) {
   const IP = getIP(request);
   const rawBanListJson = process.env.IP_BANLIST || "[]";
-  const banList = banlistSchema.parse(JSON.parse(rawBanListJson));
+  let banList: string[] = [];
+  try {
+    banList = banlistSchema.parse(JSON.parse(rawBanListJson));
+  } catch {
+    logger.error("Invalid IP_BANLIST JSON; treating as empty banlist");
+  }
   if (banList.includes(IP)) {
     logger.warn(`Found banned IP: ${IP} in IP_BANLIST`);
     return true;
@@ -47,7 +52,12 @@ export function isIpInBanlist(request: Request | NextApiRequest) {
 
 export function isIpInBanListString(identifer: string) {
   const rawBanListJson = process.env.IP_BANLIST || "[]";
-  const banList = banlistSchema.parse(JSON.parse(rawBanListJson));
+  let banList: string[] = [];
+  try {
+    banList = banlistSchema.parse(JSON.parse(rawBanListJson));
+  } catch {
+    logger.error("Invalid IP_BANLIST JSON; treating as empty banlist");
+  }
   if (banList.includes(identifer)) {
     logger.warn(`Found banned IP: ${identifer} in IP_BANLIST`);
     return true;
diff --git a/packages/lib/getSafeRedirectUrl.ts b/packages/lib/getSafeRedirectUrl.ts
index fb58fd308db..cdba43fca85 100644
--- a/packages/lib/getSafeRedirectUrl.ts
+++ b/packages/lib/getSafeRedirectUrl.ts
@@ -15,7 +15,10 @@ export const getSafeRedirectUrl = (url = "") => {
   const urlParsed = new URL(url);
 
   // Avoid open redirection security vulnerability
-  if (![CONSOLE_URL, WEBAPP_URL, WEBSITE_URL].some((u) => new URL(u).origin === urlParsed.origin)) {
+  if (![CONSOLE_URL, WEBAPP_URL, WEBSITE_URL].some((u) => {
+    try { return new URL(u).origin === urlParsed.origin; }
+    catch { return false; }
+  })) {
     url = `${WEBAPP_URL}/`;
   }
 
diff --git a/packages/lib/hashedLinksUtils.ts b/packages/lib/hashedLinksUtils.ts
index 7aae1d3d1d1..0f0e3cd53e5 100644
--- a/packages/lib/hashedLinksUtils.ts
+++ b/packages/lib/hashedLinksUtils.ts
@@ -124,7 +124,7 @@ export function isLinkExpired(
   },
   timezone?: string | null
 ): boolean {
-  if (link.expiresAt) return hasExpiryTimePassed(link.expiresAt, timezone);
+  if (link.expiresAt && hasExpiryTimePassed(link.expiresAt, timezone)) return true;
   return isUsageBasedExpired(link.usageCount || 0, link.maxUsageCount);
 }
 
diff --git a/packages/lib/hooks/useCompatSearchParams.ts b/packages/lib/hooks/useCompatSearchParams.ts
index 6a637ae1a19..1de88f75291 100644
--- a/packages/lib/hooks/useCompatSearchParams.ts
+++ b/packages/lib/hooks/useCompatSearchParams.ts
@@ -12,7 +12,7 @@ export const useCompatSearchParams = () => {
 
     // Though useParams is supposed to return a string/string[] as the key's value but it is found to return undefined as well.
     // Maybe it happens for pages dir when using optional catch-all routes.
-    const param = params[key] || "";
+    const param = params[key] ?? "";
     const paramArr = typeof param === "string" ? param.split("/") : param;
 
     paramArr.forEach((p) => {
diff --git a/packages/lib/hooks/useInViewObserver.ts b/packages/lib/hooks/useInViewObserver.ts
index 7396f2be469..072ff2ee968 100644
--- a/packages/lib/hooks/useInViewObserver.ts
+++ b/packages/lib/hooks/useInViewObserver.ts
@@ -24,7 +24,7 @@ export const useInViewObserver = (onInViewCallback: () => void, root?: Element |
         },
         {
           // We want to accept null as root
-          root: root !== undefined ? root : document.body,
+          root: root !== undefined ? root : null,
         }
       );
       observer.observe(node);
diff --git a/packages/lib/intervalTree.ts b/packages/lib/intervalTree.ts
index 1e741138564..a228266ca1a 100644
--- a/packages/lib/intervalTree.ts
+++ b/packages/lib/intervalTree.ts
@@ -32,11 +32,12 @@ export class IntervalTree<T> {
   private buildTree(nodes: IntervalNode<T>[]): IntervalNode<T> | undefined {
     if (nodes.length === 0) return undefined;
 
-    const mid = Math.floor(nodes.length / 2);
-    const node = nodes[mid];
+    const sorted = [...nodes].sort((a, b) => a.start - b.start);
+    const mid = Math.floor(sorted.length / 2);
+    const node = sorted[mid];
 
-    const leftNodes = nodes.slice(0, mid);
-    const rightNodes = nodes.slice(mid + 1);
+    const leftNodes = sorted.slice(0, mid);
+    const rightNodes = sorted.slice(mid + 1);
 
     node.left = this.buildTree(leftNodes);
     node.right = this.buildTree(rightNodes);
diff --git a/packages/lib/jsonUtils.ts b/packages/lib/jsonUtils.ts
index 3f617cb0cec..53d61c1192a 100644
--- a/packages/lib/jsonUtils.ts
+++ b/packages/lib/jsonUtils.ts
@@ -1,11 +1,8 @@
 export const validJson = (jsonString: string) => {
   try {
-    const o = JSON.parse(jsonString);
-    if (o && typeof o === "object") {
-      return o;
-    }
+    return JSON.parse(jsonString);
   } catch (e) {
     console.log("Invalid JSON:", e);
+    return false;
   }
-  return false;
 };
diff --git a/packages/lib/recentImpersonations.ts b/packages/lib/recentImpersonations.ts
index 6f6e9196724..b8a50928430 100644
--- a/packages/lib/recentImpersonations.ts
+++ b/packages/lib/recentImpersonations.ts
@@ -21,6 +21,7 @@ export function getRecentImpersonations(): RecentImpersonation[] {
 export function addRecentImpersonation(usernameRaw: string): void {
   try {
     const recent = getRecentImpersonations();
+    if (!Array.isArray(recent)) return;
     const username = usernameRaw.trim().toLowerCase();
     if (!username) return;
     const filtered = recent.filter((item) => item.username !== username);
diff --git a/packages/lib/safeStringify.ts b/packages/lib/safeStringify.ts
index 7bc6b6ba7c3..4d0ae44a11d 100644
--- a/packages/lib/safeStringify.ts
+++ b/packages/lib/safeStringify.ts
@@ -11,6 +11,6 @@ export function safeStringify(obj: unknown) {
     // Avoid crashing on circular references
     return JSON.stringify(obj);
   } catch (e) {
-    return obj;
+    return "[object could not be stringified]";
   }
 }
diff --git a/packages/lib/text.test.ts b/packages/lib/text.test.ts
index 4d60a46f140..f2999cfe343 100644
--- a/packages/lib/text.test.ts
+++ b/packages/lib/text.test.ts
@@ -1,8 +1,30 @@
 import { describe, expect, it } from "vitest";
 
-import { truncate } from "./text";
+import { truncate, truncateOnWord } from "./text";
 
 describe("Text util tests", () => {
+  describe("fn: truncateOnWord", () => {
+    it("should respect the maxLength parameter instead of a hardcoded constant", () => {
+      const text = "the quick brown fox jumps over the lazy dog ".repeat(10);
+      const result158 = truncateOnWord(text, 158);
+      const result100 = truncateOnWord(text, 100);
+      expect(result158.length).toBeLessThanOrEqual(158 + 3);
+      expect(result100.length).toBeLessThanOrEqual(100 + 3);
+      expect(result158).not.toBe("...");
+      expect(result100).not.toBe("...");
+    });
+
+    it("should preserve text when no space exists within maxLength", () => {
+      const text = "a".repeat(200);
+      const result = truncateOnWord(text, 100);
+      expect(result).toBe("a".repeat(100) + "...");
+    });
+
+    it("should return the original text when shorter than maxLength", () => {
+      expect(truncateOnWord("short", 100)).toBe("short");
+    });
+  });
+
   describe("fn: truncate", () => {
     it("should return the original text when it is shorter than the max length", () => {
       const cases = [
diff --git a/packages/lib/text.ts b/packages/lib/text.ts
index d9d28ea83d6..12f00548a93 100644
--- a/packages/lib/text.ts
+++ b/packages/lib/text.ts
@@ -8,11 +8,14 @@ export const truncateOnWord = (text: string, maxLength: number, ellipsis = true)
   if (text.length <= maxLength) return text;
 
   // First split on maxLength chars
-  let truncatedText = text.substring(0, 148);
+  let truncatedText = text.substring(0, maxLength);
 
   // Then split on the last space, this way we split on the last word,
   // which looks just a bit nicer.
-  truncatedText = truncatedText.substring(0, Math.min(truncatedText.length, truncatedText.lastIndexOf(" ")));
+  const lastSpaceIndex = truncatedText.lastIndexOf(" ");
+  if (lastSpaceIndex !== -1) {
+    truncatedText = truncatedText.substring(0, lastSpaceIndex);
+  }
 
   if (ellipsis) truncatedText += "...";
 
diff --git a/packages/lib/timezone.ts b/packages/lib/timezone.ts
index 9fd3eaac132..0b6a4a06be9 100644
--- a/packages/lib/timezone.ts
+++ b/packages/lib/timezone.ts
@@ -29,7 +29,8 @@ const formatOffset = (offset: string) =>
 
 export const handleOptionLabel = (option: ITimezoneOption, timezones: Timezones) => {
   const offsetUnit = option.label.split(/[-+]/)[0].substring(1);
-  const cityName = option.label.split(") ")[1];
+  const parts = option.label.split(") ");
+  const cityName = parts.length > 1 ? parts[1] : option.value.replace(/_/g, " ");
 
   const timezoneValue = ` ${offsetUnit} ${formatOffset(dayjs.tz(undefined, option.value).format("Z"))}`;
   return timezones.length > 0